294
regeneration, e.g., alunite due to its low cost. The main disadvantage of siliceous
materials is the fact that sorption efficiency is strongly depended on pH, e.g., application of silica beads due to low tolerance to base solutions is restricted to pH less
than 8, the chemical composition is variable, e.g., perlite and the obtained results
strictly depend on types and origin of materials, e.g., perlite (expanded or unexpanded). Siliceous material is promising adsorbents for dye removal, and physical
or chemical modification of such materials makes them even more efficient (Crini
2006; Crini and Badot 2011). Özacar and Sengil (2003) show that modification of
alunite (jarosite group, 50% of SiO 2 ) gives better sorption efficiency. Reactive blue
114 and reactive red 124 removal using unmodified alunite gives sorption capacities
equal to 2.92 mg/g for reactive blue 114 and 2.85 mg/g for reactive red 124, whereas
the sorption capacity of calcined alunite was much higher and was equal to
170.7 mg/g (Özacar and Sengil 2003). Moreover, high sorption capacities were also
obtained during the reactive yellow 64 and acid blue 40 sorption on calcinated alunite (reactive yellow 64 236 mg/g, acid blue 40 212.8 mg/g). The capacity obtained
for commercial activated carbon was lower (acid blue 40 57.47 mg/g) (Özacar and
Sengil 2002). Silica precipitated from sodium metasilicate solution by carbon dioxide in presence of ethylene glycol and modified using silane coupling agents with
the amino functionalities for reactive blue 19, acid violet 1, acid green 16, and acid
red 18 removal was obtained by Krysztafkiewicz et al. (2002). There was found that
except for acid green 16, dye adsorption efficiencies were independent on the type
of aminosilane used for modification. Glass powder; dolomite, e.g., charred dolomite; perlite (glassy volcanic rock of high silica content >70%); silica; and modified
silica found also applicability for reactive, basic, and acid dyes removal, e.g., for
acid red 44 (sorption capacity 4.03 mg/g) (Atun and Hisarli 2003), brilliant red
E-4BA (sorption capacity 950 mg/g) (Walker et al. 2003), methylene blue (Dogan
et al. 2004), and methyl violet (Dogan and Alkan 2003) as well as for basic blue 9
(sorption capacity of unmodified silica 11.21 mg/g) (Woolard et al. 2002) and acid
blue 25 removal (sorption capacity of modified silica 45.08 mg/g) (Phaan et al.
2000). As was pointed out sorption on perlite is physical.
Another group of siliceous materials are zeolites, aluminosilicate minerals of
porous structures containing cavities. They possess three-dimensional structure of
negative charged balanced by cationic ions able to exchange reaction which other
cations present in solutions. The main representative of zeolites is clinoptilolite
which is a mineral of the heulandite group and the most frequently tested in terms
of its sorption properties. Ghobarkar et al. (1999) review the applications of zeolites
and present their useful properties. Zeolites are characterized by open and highly
porous structures of easy access, high surface area, and sorption capacity as well as
selective affinity for certain pollutants (dyes, phenols, heavy metal ions) and low
prices which depends on their quality (0.03–0.12 $/kg) (Crini 2006; Crini and Badot
2011). As was observed by Armagan et al. (2004) and Ozdemir et al. (2004), natural
zeolites have restricted applicability for reactive dyes removal such as everzol red,
everzol black, and everzol yellow due to the low sorption capacity; therefore they
need additional modification. Zeolites surfaces modification with quaternary amines
or hexamethylenediamine improved their sorption ability toward reactive dyes, e.g.,
A. Wołowicz and M. Wawrzkiewicz
regeneration, e.g., alunite due to its low cost. The main disadvantage of siliceous
materials is the fact that sorption efficiency is strongly depended on pH, e.g., application of silica beads due to low tolerance to base solutions is restricted to pH less
than 8, the chemical composition is variable, e.g., perlite and the obtained results
strictly depend on types and origin of materials, e.g., perlite (expanded or unexpanded). Siliceous material is promising adsorbents for dye removal, and physical
or chemical modification of such materials makes them even more efficient (Crini
2006; Crini and Badot 2011). Özacar and Sengil (2003) show that modification of
alunite (jarosite group, 50% of SiO 2 ) gives better sorption efficiency. Reactive blue
114 and reactive red 124 removal using unmodified alunite gives sorption capacities
equal to 2.92 mg/g for reactive blue 114 and 2.85 mg/g for reactive red 124, whereas
the sorption capacity of calcined alunite was much higher and was equal to
170.7 mg/g (Özacar and Sengil 2003). Moreover, high sorption capacities were also
obtained during the reactive yellow 64 and acid blue 40 sorption on calcinated alunite (reactive yellow 64 236 mg/g, acid blue 40 212.8 mg/g). The capacity obtained
for commercial activated carbon was lower (acid blue 40 57.47 mg/g) (Özacar and
Sengil 2002). Silica precipitated from sodium metasilicate solution by carbon dioxide in presence of ethylene glycol and modified using silane coupling agents with
the amino functionalities for reactive blue 19, acid violet 1, acid green 16, and acid
red 18 removal was obtained by Krysztafkiewicz et al. (2002). There was found that
except for acid green 16, dye adsorption efficiencies were independent on the type
of aminosilane used for modification. Glass powder; dolomite, e.g., charred dolomite; perlite (glassy volcanic rock of high silica content >70%); silica; and modified
silica found also applicability for reactive, basic, and acid dyes removal, e.g., for
acid red 44 (sorption capacity 4.03 mg/g) (Atun and Hisarli 2003), brilliant red
E-4BA (sorption capacity 950 mg/g) (Walker et al. 2003), methylene blue (Dogan
et al. 2004), and methyl violet (Dogan and Alkan 2003) as well as for basic blue 9
(sorption capacity of unmodified silica 11.21 mg/g) (Woolard et al. 2002) and acid
blue 25 removal (sorption capacity of modified silica 45.08 mg/g) (Phaan et al.
2000). As was pointed out sorption on perlite is physical.
Another group of siliceous materials are zeolites, aluminosilicate minerals of
porous structures containing cavities. They possess three-dimensional structure of
negative charged balanced by cationic ions able to exchange reaction which other
cations present in solutions. The main representative of zeolites is clinoptilolite
which is a mineral of the heulandite group and the most frequently tested in terms
of its sorption properties. Ghobarkar et al. (1999) review the applications of zeolites
and present their useful properties. Zeolites are characterized by open and highly
porous structures of easy access, high surface area, and sorption capacity as well as
selective affinity for certain pollutants (dyes, phenols, heavy metal ions) and low
prices which depends on their quality (0.03–0.12 $/kg) (Crini 2006; Crini and Badot
2011). As was observed by Armagan et al. (2004) and Ozdemir et al. (2004), natural
zeolites have restricted applicability for reactive dyes removal such as everzol red,
everzol black, and everzol yellow due to the low sorption capacity; therefore they
need additional modification. Zeolites surfaces modification with quaternary amines
or hexamethylenediamine improved their sorption ability toward reactive dyes, e.g.,
A. Wołowicz and M. Wawrzkiewicz